Microchemical Laboratorv of the Abbott Laboratories E. F. SHELBERG, Abbott Laboratories. Uorth Chicago, 111.
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THE year 1910 Fritz Pregl, finding it necessary to analyze minute quantities of biochemical substances, developed a system of milligram analysis which is the basis of modern microchemical technique. Since this time, industrial and research chemists have discovered to an ever-increasing extent the value of a microchemical laboratory, and in 1934 Abbott Laboratories decided to install a microchemical division. Prior to 1934 numerous samples were being analyzed for both the research and manufacturing departments and there were times when the large volume of analytical work could not be handled with sufficient promptness. This was especially true when it became necessary to analyze a series of sample. using macromethods such as the Dumas, the Kjeldahl, or the carbon and hydrogen Not only did these analyses require large samples, but the determinations were also lengthy, and in many instances finished products could have been made before i t was possible to analyze the intermediates. Microchemical methods, hoT5 ever, brought about more efficient service for both the research and the manufacturing departments. The first microchemical laboratory was equipped primarily for Dumas, Kjeldahl, and carbon and hydrogen determinations. This laboratory was not air-conditioned, and there was no system to control the humidity. A Kuhlmann micro-
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balance n-a? installed on a very rigid support which, nevertho less, allowed the balance to vibrate to a certain extent. The Research Building (1) erected during 1937, includes the new microchemical laboratory. The floor plans show its location ( L . 11.2.) on the second floor. The advice of chemists and chemical engineers both in universities and in industry was sought and utilized in planning its construction.
Rooms and Furnishings The walls of the laboratory are of a cream-colored, matglaze terra cotta. Excellent light is furnished from overhead lighting fixtures of a semiindirect type. Light can also be obtained through a large glass-brick window. The laboratory consists of a large room for analyses and a smaller room for weighings. Both rooms are completely airconditioned; the air is washed and then passes through a filter of glass wool impregnated with oil, before it enters the room through a n “Anemostat” in the center of the ceiling (not shown in picture) that distributes the air eyenly without creating drafts. The air-conditioning equipment is adequate to care for more than twice the space now used. After experimenting to decide the most desirable temperature and humidity, it was found that a temperature of from 7 3 ” to 7 5 “ F. and a humidity of 50 per cent were satisfactory, and these are maintained in the laboratory. d humidity in
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excess of 50 per cent is less satisfactory because it sometimes causes the microbalance to stick. A recording instrument registers the temperature and humidity and furnishes a weekly graph of both. The operation of the hood in the microlaboratory does not appreciably change the temperature or humidity. The laboratory furniture is made of steel, lead-coated with aluminum finish; the desk tops are a black asbestos-cement-
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asphalt composition Sumerous drawers and cupboards are provided, and, as they are installed in units, they can be changed a t any time. The cupboards are either attached to the Tvall or rest upon especially made units containing drawers, and are large enough t o store the reagents and much of the equipment. The laboratory tables are liberally fitted with facilities for gas, electricity, vacuum, compressed air, and water (tap and distilled). All water taps are provided with drains. I t has been found that the large dimensions of the room aid the analyst’s operations by providing ample space so that certain apparatus can be set up permanently. The balance room is of rectangular shape. and houses three balance cases which conveniently house the four balances used, and, like the rest of the furniture, are made of steel with aluminum finish. The cases are 30 inches high and 18 inches deep; two are 30 inches wide and one is 36 inches wide. They are attached to the wall and are separate from the HOOD tables on which the balances are I mounted. Lightr i n g is obtained from movable l i g h t s that slide on a rail directly over the balance cases.
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FLOOR PLAXSOF RESEARCH BUILDIXG C.
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Conference room Dark rooms Elevator Freight receiving Janitor Laboratories Analytical Bacteriological Biochemical Botanical Microsnalytical Organic Pharmaceutical
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Li. Library Li.0. O5ce, Li.R. Reading rooms L i S . Stack room iM. Medical first aid 0. Offices R. Rest room S. Storage S.C. Cold room S . H . Warm room S.S. Sample storage T. Toilets W. Reception room
Equipment Samples requiring the same type of analysis are encountered so frequently that much of the equipment is set up perma-
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nently. The Kjeldahl apparatus, f o r e x a m p l e , is used r e p e a t e d l y . T h e Parnas-TT'agner niodification w i t h a n i m p r o v e d method of withdrawing t h e excess liquid from n ithin the vacuum jacket is used for Kjeldahl distillations. Instead of waiting for the water in the steam-generating flask to cool of its own accord, cold distilled water is added quickly from a seDarate inlet connected to *the flask. This not only saves time, but i t also keeps the steamgenerating flask filled with the proper amount of water. A special rack xithin the large hood has been provided for Kjeldahl digestions. This has a fume duct, cylindrical in shape and mounted horizontally, from 1% hich fumes are removed by a separate fan. There are openings in the bottom of this fume duct into which the necks of the Kjeldahl flasks are inserted. Microburners are used for the digestions. The digestion of a 2- to 5-mg. sample is made with 1 cc. of fuming sulfuric acid and a small amount of selenium. Thirty per cent hydrogen peroxide is added during the digestion to aid the destruction of the coinpound. I n many cases nitrogen mubt be determined by the Dumas method. An electric furnace is used to heat the
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combustion tube, but the sample is burned wit'h a Bunsen burner. A Poth generator (6) is used to furnish t,he carbon dioxide. It is more convenient and requires less space than a series of Kipp generators and produces pure carbon dioxide a t all times. Also, refilling is seldom necessary. The top and side arm of this Poth generator are not sealed off after filling, as is usually done. Instead, the apparatus has ground-glass stoppers sealed with Kroenig cement. X bent acid-delivery tube has also been found to be advaritageous, as it prevents lag in carbon dioxide evolution. When the acid-delivery tube is not bent, crystals form a t the surface of the liquid around the tube. If this formation is allowed to continue until i t covers a large area, there is a lag in t'he carbon dioxide evolution due to the fact that it takes some time for the acid to come into contact n-ith the bicarbonate solution. Standard inicro equipment is used for carlion and hydrogen determinations, and like the Kjeldahl and Dumas apparatus is never dismantled. The laboratory is equipped m-ith many other t'ypes of apparatus for standard microanalyses, including the follon-ing: halogens, sulfur, acetyl, methoxyl, and molecular n-eights. Melting points are taken on the Kofler microscopic hot stage. Qualitative analyses and spot tests ( 2 , 3 ) can be made. S o t only are organic compounds analyzed, but occasionally inorganic compounds are al:\o anaIyzed by micromethods. Four balances are used: a micro-Kuhlmann, a microBunge, a semimicro-Christian Becker, and a Sartorius preliminary balance. The t,wo microbalances and the semimicrohalance are mounted on hand-ball suspensions (4, b ) , which are very efficient in reducing vibration t'o a minimum and in ensuring a constant zero point. A hood is conveniently located next t'o the sink and is equipped with a safety light and a safety-glass R-indow. On one side in the hood there is a reagent cupboard with glass doors; on the other side, the Kjeldahl digestion rack is located. Gas, electricity, vacuum, and water are provided in the hood and may be controlled from without as well as froni within.
Literature Cited
MICRO-KJELDAHL DISTILLATIOS
-APP4R.4TUS KITH C O O L E D STEAM-GENERATING FLASK
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After water is added t o the steam-generating flask, the liquid in the vacuum jacket will be immediately transferred to the discharging flask. The liquid can then be emptied into the drain. Pumice stone is a n excellent material t o prevent bumping in the generating flask.
(1) Abbott Laboratories, ISD. ESG. CHE&f.,N e w s E d . , 16, 533 (1938). ( 2 ) British Drug Houses, G r a h a m St., London N. 1, England. "Reagents for Spot Tests." (3) Feigl, F., "Spot Tests," Kew Tork, N o r d e m a n n Publishing Co.. 1937. (4) Kirner, W. R . , ISD.ESG. C H E J f . , .Inal. Ed., 9, 300 (1937). ( 5 ) Kiederl a n d Niederl, "Organic Q u a n t i t a t i v e Analysis," 11. 9. Kew York, J o h n W l e y 8: Sons, 1938. (6) P o t h , E. J., ISD.EXG.CHEM.,Anal Ed., 3, 202 (1931). RECEIVED October 2 1 , 1938
